Broadly speaking, there are two ways to understand descriptive comparisons between players from different eras.
One is a matter of convenience. Outlining the nuances in a footballer's game can be quite onerous, and can often involve language that is inscrutable to the layman. Also, it helps to establish what the benchmark is for relative terms like 'speed' and 'dribbling': saying a player is quick will likely elicit the question 'as quick as so-and-so?'
The other is a matter of accessibility. There is a lot of football played in the world, and few have a handle on all of it.